A stroke or cerebrovascular accident (CVA) refers to a rapid loss of brain function due to a disturbance in the brain's blood supply, for example, due to a lack of blood flow (referred to as ischemia) caused by blockage, e.g., thrombosis or arterial embolism, or a hemorrhage. Stroke is the second leading cause of death worldwide and the third leading cause of death in the United States, between cardiac diseases (the number one worldwide common cause of death) and tumor diseases (the number three worldwide common cause of death). The majority of acute ischemic strokes (80%) are caused by thrombo-embolism, and in comparison to, e.g., cardiac and tumor-related diseases, the amount of acute cell death in ischemic stroke during the initial phase of a stroke event is significantly greater. That is, neuronal brain cells (neurons) are very sensitive to oxygen supply, which may be interrupted, for example, due to a sudden arterial vessel occlusion. Thus, neurons turn into apoptosis within the first 60 seconds of oxygen deprivation. Apoptosis is defined as a programmed cell death, which means that neurons start to die irreversibly even at this very early point in time if recanalization, and therefore providing an oxygen supply, does not occur.
FIG. 1 illustrates one example of a normal vessel, indicated by arrow 100, an example of an occluded vessel, indicated by arrow 110, and an example of a recanalized vessel at, e.g., 25 minutes after occlusion, indicated by arrow 120. FIG. 1 further illustrates an example of a blood clot 130, as observed prior to the application of ultrasound treatment, as well as an example of a blood clot 130, as observed post-ultrasound application.
In the case of acute ischemic stroke, it has been shown that an average of 1,900,000 neurons die every minute due to intracranial arterial vessel occlusion. Hence, it is a worldwide, common understanding that therapeutic options to recanalize the affected brain artery should be applied as early as possible. Recent advances in stroke care, such as the installation of specialized Stroke Centers/Units or TeleMedicine concepts, have improved stroke care in selected areas. However, all of these activities are either initiated or coordinated mainly by well-known academic centers in developed countries, and the overall impact of these improvements on stroke care are negligible.
It should be noted that the cause of the worldwide growing incidence of stroke may be attributed to three main causes. First, there is a lack of public awareness of the disease and its symptoms. Second, all conventional therapeutic interventions require hospitalization of the patient. Third, and among people of all ages, more than 85% of global deaths from stroke occur in either low or middle-income countries, where approximately 85% of the world's total population resides. FIG. 2 illustrates that deaths attributable to stroke in middle income individuals was approximately 3 million in the early 2000s, and is increasing, as indicated by line 210, almost 2 million for low income individuals and also increasing, as indicated by line 220. In contrast, and as indicated by line 230, deaths attributable to stroke amongst high income individuals in the early 2000s and projected through 2030 remains under 1 million.
Currently, there is no known therapeutic option which allows the treatment of acute stroke patients to begin “in the field,” e.g., at the site of the emergency and/or during transport to a care facility, such as a hospital. In the field treatment can be considered to be of critical importance since the majority of strokes occur in suburban or rural areas, often a great distance from specialized stroke centers. In these cases, the time delay between an emergency call, e.g., 911 call, arrival at the site of the emergency, and transport to the specialized stroke center may often be a limiting factor as to whether a patient survives, suffers from lifelong invalidity, or fully recovers without any deficits.
One recently developed device, which aims to treat stroke victims using ultrasound, is a device, referred to as the CLOTBUST™-ER by Cerevast Therapeutics, Inc. However, the CLOTBUST™-ER ultrasound stroke treatment device has been developed for stroke treatment in an emergency room, after a patient's admission to a hospital, and in combination with Tissue Plasminogen Activator (tPA), currently the only FDA approved lytic drug for stroke treatment. Accordingly, and again, even with such a device, treatment in the field remains lacking for stroke victims.